Key radar fails on $1bn Nasa environmental satellite

FLORIDA, September 4, 2015

A key instrument on a $1 billion Nasa satellite has failed, reducing scientists' ability to capture data to measure the moisture in Earth's soil in order to improve flood forecasting and monitor climate change, officials said on Thursday.

A second instrument remains operational aboard the 2,100-pound Soil Moisture Active Passive satellite, though its level of detail is far more limited.

The satellite's high-powered radar system, capable of collecting data in swaths of land as small as about two miles across, failed in July after less than three months in operation, Nasa said. The cause of the failure is under investigation.

Launched in January, SMAP was designed to spend at least three years in orbit, taking measurements on the amount of water in the upper two inches of the Earth's soil.

Scientists had hoped to combine SMAP's high-resolution measurements with data from the lower-resolution instrument to get a better understanding of how much water, ice and slush is in the planet's top soil.

"The project will do all it can to meet the expectations of the science community," lead researcher Dara Entekhabi, a professor at the Massachusetts Institute of Technology, told Reuters in an email.

He said scientists would rely on advanced data processing, coupled with other data from the mission, to help fill in gaps.

"What I will miss most about the SMAP radar is the opportunity for chance discovery. It was unique among the other instruments in orbit now because it provided frequent microwave mapping of the Earth's surface," he said.

Efforts to troubleshoot the problem were not successful, and Nasa this week declared the radar system failed.

Overall, soil moisture accounts for less than one per cent of the planet's total water reservoir, with 97 per cent in the planet's oceans and nearly all of the rest locked in ice, Entekhabi told reporters before SMAP's launch in January.

Currently, scientists estimate soil moisture using computer modeling.

The tiny amount of soil moisture links Earth's environmental systems - its water, energy and carbon cycles - as well as determining whether particular regions are afflicted with drought or flooding.

"It's the metabolism of the system," Entekhabi said in January. - Reuters